Wednesday, December 10, 2008

This isn't your mother's melamine - or is it?

Melamine is yet another cool ‘50s invention that failed to enter my mother’s kitchen. While friends and neighbors stocked up on the nifty new light, durable and colorful plastic dishware, my mother filled her kitchen with white, pure white, simple, elegant, breakable ceramic. Her cupboards are still filled with the stuff – white, white, white. Not so at my in-laws, where the everyday dinner ware is red, blue and yellow melamine, pleasingly smooth, tough and virtually unbreakable.

Just a couple of years ago, Crate and Barrel in an effort to appeal to boomers who recall dining off the colorful plastic, offered melamine in colors that harkened back to the fifties and sixties – bright orange, acid green and red (far better on plates than on the cabinets and counters) and, being deprived of the plastic as a child, I pounced, buying a cute set of eight orange, green and red oval-shaped melamine dishes.

This is all to say that until a year or so ago any thoughts I had about melamine were pleasant and nostalgic. Now when I think melamine, I hear the rattle-snake sound of the old westerns, the sound that happens just before something bad is about to happen. Just before the good guy is about to drink the tainted water, or the heroine is about to drink the poisoned wine.

Chemically, melamine is a pleasingly round molecule made up of hydrogen, carbon and nitrogen, and is used in the preparation and production of a range of items including house wares, flame retardants, and fabrics. When combined with formaldehyde and heated up – melamine is transformed into the dinnerware. Which by the way, when heated together with your favorite acidic food, (reheated tomato sauce anyone?) can release upwards of 2.5 milligrams of melamine per 100 cm2 according to the National Toxicology Program, that’s roughly 2.5 mg per one big round plate – but that’s a separate issue.

By itself, melamine’s acute toxicity is comparable with that of table salt (i.e. not very toxic) although recall that toxicity is often a moving target depending on the sensitivity of the endpoint, exposure duration, age of test subject and other considerations. That melamine causes kidney toxicity following longer exposures to high concentrations in test animals (say 2 – 4 parts per thousand in feed,) is well known and until now, not considered highly relevant, because those concentrations were considered unrealistically high. Here I’d emphasize were, but we’ll get back to that later.

What first brought melamine to our attention here in the states, is the toxic transformation that occurs when it combines with cyanuric acid, an FDA approved feed additive, also used to produce dyes, herbicides, antimicrobials and pool water disinfectant. That's when the "watch out" snake start rattling. Cyanuric acid, a derivative of melamine is also a ringed nitrogen containing structure, and like melamine it is considered not acutely toxic. But when these two chemicals get together, like the Witches of Eastwick, the mayhem begins. Following ingestion, the chemicals make their way to the kidney destined for simple excretion. Unfortunately should they meet up, melamine and cyanuric acid join together to forming melamine cyanurate crystals, a toxic combination capable of lodging in kidney tubules and causing acute renal failure and death.

A year ago contaminated pet food from China was implicated in the deaths of dozens of cats and sickened thousands of dogs and cats. The culprit was subsequently traced to melamine tainted gluten. Gluten, derived from wheat or rice, is a common source of protein. Protein is sometimes estimated by measuring gluten nitrogen content. Given the high amount of nitrogen groups in both melamine and cyanuric acid (available as “scrap residue” from the melamine industry) it isn’t hard to imagine unscrupulous processers adding the stuff to their products to dupe purchasers or regulators into thinking they were selling a higher protein product.
After the massive recall of over 150 brands of pet food one would think that the incident alone would deter anyone from trying the same thing again, at least anyone with a conscience. But sadly, like the string of corrupt Illinois politicians, there’s always someone next in line no matter the consequences.

This past fall over 50,000 infants became ill, and at least four died of kidney failure after drinking melamine laced formula in China. The scandal soon spread beyond formula to candy, milk, and other diary containing products produced by dozens of companies. To date, only melamine has been implicated – leaving scientists to wonder about the mechanism of toxicity – recall with the pet foods melamine was mixed with its evil twin, cyanuric acid.

According to the World Health Organization upwards of 6196.61 mg/kg have been measured in dairy products including infant formula. That’s 6 grams in one kilogram of product, or, 6 parts-per-thousand. While that may be the high end, recall the sub-acute toxicity tests mentioned above and those screamingly high concentrations now seem more relevant. Additionally, chemicals are most often tested in weaned animals – not nursing animals – so concentrations that might be OK for adults may not be OK for the very young.

The Sanlu Group one of China’s major diary and infant formula producers whose products were fist shown to contain the chemical quickly blamed the dairy farmers – suggesting that they were the ones who added melamine to fool protein tests.
More recently, according a news article in the journal Science, investigators concluded that the adulterated infant formula was “nothing short of a whole-sale re-engineering of milk,” a skill likely out of reach for dairy farmers, but perhaps not for milk-collecting companies or corporations higher up the milk-chain.

China’s response to the tragedy, according to Science, is to pledge greater transparency and vigilance. In addition, China plans to open Food and Drug Administration offices here in the U.S. and the US FDA recently opened three offices in China. But old habits die hard and according to Chen Junshi a risk assessment specialist at China’s Center for Disease Control and Prevention, and quoted in Science, it’s likely that food adulterers will only become cleverer. Those willing to make money at the expense of their fellow citizens, will seek alternative methods challenging both Chinese agencies and the newly opened US Food and Drug Administration offices in China.

Now, about those colorful plates...

13 comments:

Anonymous said...

Dear Dr. M,

I think I have eaten tomato sauce mixed with melamine at your in-law's house. Your sister-in-law has some brightly colored plates, too. When you refer to "heating" the melamine with the acidic sauce, is the heat of the sauce enough to "heat" the melamine? Although I'm not a big fan of white, your mom does have style.

Emily Monosson said...

You know I just realized that aside from those colorful plastics I too have all white plates - how that could have slipped my mind I have no idea! Sense of style or a subconscious desire to recreate my childhood?

In this case heating refers to 70C for 2 hours,(and multiple use products were tested multiple times.) A 70C temperature was chosen over the alternative 100C for 15 minutes(e.g. a cooling cup of coffee) because researchers consider it a more rigorous test.

While researchers reported some migration from many different types of bowls and plates (Barbie dishes, Winnie the Pooh, Thomas the Tank Engine - you name it) concentrations were below the “specific migration limits” set by the European Commission.

But, recall that these are also made with formaldehyde, and guess what? That leaches too! Again in most cases at levels below those "allowable" by the EC - though a few were higher. Those that were high were subsequently recalled (this particular study was published in Journal of Food Additives and Contaminants by Bradley et al., Survey of the migration of melamine and formaldehyde from melamine food contact articles available on the UK market, 2005,22:597-606 if you want to read more.)

Just Another Obscure Author said...

You are brilliant! I love your blog, and I think this post in particular is outstanding. I've linked to you on my blog. Thank you for making complicated chemistry matters fun to read about.

Emily Monosson said...

Aw shucks. Thank you for your encouraging words. Your blog is quite interesting and informative as well, and as soon as I figure out how to add links (again - it's been so long and I fumble through these things) I will add yours to this site.

Emily

JLowe said...

Hi Emily,

Once again, nicely done. I haven't paid a great deal of attention to melamine issues, and your characterization of the risks was very clear, understandable and in perspective.

We've got all sorts of roadmaps for how to get people involved with thinking about health risks (as examples, the NRC's Understanding Risk and Advancing Risk Assessment reports), but it's the grassroots efforts such as yours where the real work in communicating risks is getting done.

Debbie Monosson said...

..hmmm I noticed you only use the melamine plates when your family comes to visit...

Anonymous said...

I unwittingly heated food contained a melamine bowl in the microwave and fed the food to my two-year old child. I did this on about 12 occasions. Did I endanger my son's health? Are there any tests to determine any damage? Any remedies if there has been harmful exposure?

andrewlylehartman said...

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Emily Monosson said...

Anon, while I can't comment on amounts that may have been released from your dishes, I can refer you to a study by Bradley et al, (Bradley et al., Survey of the migration of melamine and formaldehyde from melamine food contact articles available on the UK market, 2005,22:597-606) where they surveyed different melamine kitchen-ware. While some released more than others, all were found to be below the European Commission's "allowable" concentrations - for all that might mean - though at least we know for all the melamine in use - there haven't been any reported toxicity from unintentional release (vs the intentional addition and release from baby formula.)

Those concentrations were way higher than amounts released from dishes - and those dishes were subjected to fairly harsh conditions - though I don't know how they'd compare with microwaving. I couldn't find any articles on the release of melamine from microwave cooking (usually it's not recommended just because the dishes get hot or don't do well in the microwave.)

Anonymous said...

...well I was just served lunch on the orange melamine once again..and I feel healthier than I did before! Thanks Em!!

jenijett said...

What are your thoughts on the safety/toxicity of bamboo-based BPA-free melamine plates? Thank you.

jenijett said...

Dear Dr. M
What are your thoughts on the toxicity of bamboo-based BPA-free melamine dishware? Safe or not so safe?

Emily Monosson said...

Hi Jenijett:

That's a good question. First, advertising BPA-free melamine is a bit like advertising fat-free or cholesterol-free celery (it doesn't have any, and never has.) That said, I've been away from the blog for a while, not keeping up with new and different products. I did a little poking around - and its hard to find much on the stuff. I did find that some products are blends of melamine and bioplastic or bamboo based "plastic." Am finishing up another project right now, but when I have some time, I'll try to find out more on the bamboo. It seems there must be some binders, additives or something, which may be OK, or maybe not, only time will tell (as it always does!)